Trailer light connector systems are well known in the art. The systems differ slightly depending upon the model and type of towing vehicle.
In a pick-up truck for example, the factory installs, as original equipment, electrical wiring for the cab and electrical wiring for the chassis. The cab wiring and chassis wiring are electrically interconnected by a plug having male terminals and a plug having female terminals cooperatively coupled as a plug set to complete the electrical circuit therebetween.
A T-shaped connector may selectively be interposed between the plugs of the plug set to retain the overall vehicle circuit while providing a tap for electrical power to a trailer. T-shaped connectors of this type have been commercially available from the assignee of the present invention and from its predecessor in interest, Olathe Automotive Wiring Company. The prior art T-shaped connector included a plurality of individual insulated wires extending outwardly from the T-shaped connector body for the trailer tap. These insulated tap wires from the T-shaped connector body were then hard wired to the vehicle end of a trailer wiring system. This hard wiring of the trailer tap to the trailer wiring system was inconvenient and time consuming and required care and experience in matching the tap wires of the T-shaped connector to like wires in the trailer wiring system. In addition, at times, special tools, such as a soldering gun, were required to complete the hard wiring process.
Another type of trailer light connection system utilizing a different type of T-shaped connector is shown in Hopkins et al., U.S. Pat. No. 4,842,524. The T-shaped connector has a body with three terminals. The first terminal is adapted for connection to a male vehicle wiring plug, the second terminal is adapted for connection to a female vehicle wiring plug to complete the vehicle electrical circuit, and the third terminal (constituting a tap plug) provides a source of electrical power for the trailer. A wiring harness having a first harness plug is removably coupled to the tap plug at one end and is coupled to the trailer light system at its other end to complete the electrical connection between the vehicle and the trailer.
The T-shaped connectors described in Hopkins U.S. Pat. No. 4,842,524 contribute important advantages to a connection system using modular components. The modular system facilitates connecting the trailer light electrical system with the towing vehicle electrical system and reduces the number of stockkeeping units needed. However, the T-shaped connectors shown in the patent lack a certain amount of flexibility in being able to provide a standarized tap plug which can be used with trailers having backup lights and with trailers which do not. More particularly, a tap plug having four terminals is typically used to provide power from a towing vehicle to a trailer with backup lights. The four terminals provide right and left turn signal functions, brake light functions and back-up light functions, respectively.
However, if the trailer does not have backup lights, only three of the terminals are necessary, and consequently, the extra conductor leading from the T-shaped connector for the backup lights on the trailer is unused. In this case, the unused conductor is typically cut, and the cut portion leading from the tap plug is stripped and connected to a ground on the towing vehicle to provide an electrical ground between the trailer and the towing vehicle. This hard wiring, however, can be inconvenient and time consuming to install, and does not always provide a reliable electrical connection.